Creo 3 Lighting - Dark Spots

Creo 3, M040

I'm having issues with lighting in Creo 3.  I have this in my config to tell Creo what lighting scene to use:

default_scene_filename P:\config\01_user\doug\creo_3\Basic-studio-blend-gray.scn

I saved that "Basic-studio-blend-gray.scn" file out of Creo 3.  I did this in Creo 2 and it generally worked well, although I would occasionally have to reset the scene because Creo had forgotten.

In Creo 3 the lighting changes all the time.  I spin the model 180 degrees and the near side is in the dark.  If I reapply that scene it comes back to normal.  I tried with and without the "lock room to model" box checked with no difference.

How do I get my lights to stay put?